Puma is using one process most of the time

Question

I configured puma to use 3 processes and 1 thread. In application I am currently checking I have one really long request (~60 s). Problem is that puma is using mostly one process to run requests. So, I have:

p  - puma main process
p1 - puma process 1
p2 - puma process 2

rn(x) - request number n that takes x second

so in such pipeline (request are fired in more less same time):

r1(0.2), r2(0.1), r3(60), r4(0.3)

the puma queue looks like this:

    __________ p1: r1(0.2), r2(0.1), r3(60), r4(0.3)
  /
p
  \ __________ p2: iddle

what makes waiting for r4 for ages?

Why it is happening?

Answer 1

Ok, VM machine has one core. Added more and is working like a charm.